Tracked vehicles are often provided with a track assembly pair consisting of two track assemblies disposed on a respective side of the vehicle body.
The present invention concerns the type of tracked vehicle(s) where support wheels (against which the track runs) and drive wheels (which drive the track) of the track assemblies are rotatably journaled in a track support beam, which in turn is suspended in the vehicle body and typically in a so-called chassis beam or center beam of the vehicle body. This is different from tracked vehicle(s) where drive wheels and support wheels are journaled directly to the vehicle body and therefore has no separate track support beam. Thus, the track support beam constitutes a structural element, comprised in certain tracked vehicle(s), arranged to support a ground-contacting endless track running about the track support beam for propulsion of the tracked vehicle.
Tracked vehicle(s) of the type to which the present invention is derived typically comprises two track assemblies, each one comprising a respective track support beam, where each track support beam is connected to, or suspended in an intermediate chassis beam via construction elements, herein referred to as trailing arms.
The part of the track assembly suspension that the present invention mainly refers to is the actual attachment between the track support beam and the trailing arm connecting the track support beam to the chassis beam or other part of the vehicle body.
There are many alternatives on track assembly suspensions and attachments between track support beams and chassis beams and the requirements of these naturally depends partly on the type of tracked vehicle(s).
In conventional tracked vehicles where the drive motor is mounted in the vehicle chassis and typically supported by a chassis beam the connection between the chassis beam and track support beam have to comprise mechanical/hydraulic solutions for the transmission of drive torque to the drive wheels of the track assembly. Examples of such conventional solutions are shown in inter alia US 2007169968 and US 2008156548.
In more unconventional types of tracked vehicles, such as the tracked vehicle disclosed in the present application, the drive motor driving the drive wheel is integrated in the track assembly, wherein each track assembly thus constitutes an independent drive unit. In this case it is typically enough that control signals are transmitted from a central control unit on the vehicle body to the respective track assembly. As the mechanical/hydraulic solutions for torque transmission are not necessary in this case, the suspension devices can appear substantially different. The present invention will be described in the context of such a tracked vehicle, which tracked vehicle is more detailed described in the international patent application PCT/SE2014/050563. Other examples of tracked vehicle(s) with track assemblies that can be seen as independent drive units are described inter alia in patent applications GB128280A, US2003116366 and CN202175123U. In GB128280A, however, the drive wheels are journaled in the vehicle body, such that the track assembly therein cannot be said to constitute an independent drive unit.
Although the invention particularly relates to a suspension device for track assemblies of the kind described above, i.e. for track assemblies constituting independent drive units, the invention is applicable to all types of track assemblies comprising a track support beam to be connected to a chassis beam or other structural element constituting part of a vehicle body of a tracked vehicle.
The attachment device for attachment of the trailing arm to the track support beam is a key component of the track support beam and constitutes one of the points in which the track support beam carries the load of the vehicle body. This sets high demands on the structural strength of the attachment.
Known types of attachments between trailing arms and track support beams suffer inter alia of that they are weak in construction, which reduces the life expectancy and increases the service needs of the tracked vehicle. Furthermore, they are not formed to allow adequate suspension between the track support beam and the vehicle body (chassis beam), which reduces the comfort during propulsion of the vehicle and/or reduces the life expectancy/increases the service needs of the vehicle. Typically, they are also complex in construction, which makes them difficult and expensive to manufacture and assemble.
Accordingly, there is a need for improvements within the field of suspension of track assemblies of tracked vehicle(s), and in particular in the field of attachment devices for attachment of a trailing arm adapted to couple a track support beam to a chassis beam or other structural element of a vehicle body.